We recently reported the synthesis ofa new class of acylpalladium (II) complexes, which show significant anti tumor activity against P-388 mouse leukemia. We propose to synthesize a series of related and analogous organopalladium and platinum complexes using rapid on-site bioassay to direct the synthetic effort towards complexes of high activity. The synthetic method allows wide structural variation with no change in procedure. In this fashion, complexes of maximum antitumor activity will be synthesized, and some information on structure-activity relationships will be gained.